Jitter Question

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What is an acceptable Jitter Rate for an SLA with a service provider?
MY provider is saying that they will guarantee that jitter will not go
above 10 milliseconds and it will be measured in 5 minute intervals.


This is an MPLS network and we will run IP voice over this network.
What amount of Jitter can cause voice communication problems? Is it 8
milliseconds?


Thank You for any responses, all responses are greatly appreciated.
Have a wonderful day.


Re: Jitter Question
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it depends on the codec setting, and the buffer settings (and the
capabilities of the VoIP reciever).

you need a deep enough de-jitter buffer to cope with the jitter you have.

Since the buffer directly adds to the overall path delay, you want that to
be low for lowest delay, but more jitter pushes up the number.

there is some inherent jitter in an IP system that the phones have to cope
with - for example a router sending you packets down a x Mbps line sends a
1500 byte packet 1st, so your voice packet has to wait.

at 2 Mbps, 1500 bytes, is 12k bits, so roughly equivalent to 6 mSec, and
slower lines get proportionally worse. And many networks have multiple slow
hops, each of which can add to the jitter.

The overall target VoIP delay budget is something around 150 mSec 1 way -
but that includes distance, store and forward, codec delay etc.

So - if your IP phone cannot cope with a few 10 of mSec of jitter, then it
is going to have problems on a WAN.

a cisco bit:
http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a00800945df.shtml
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Regards

stephen_hope@xyzworld.com - replace xyz with ntl



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